I noticed that Zwift reports active calories only (i.e., mechanical work done), whereas Garmin activities seem to sync total calories to intervals (mechanical work done + resting calories). This is quite a big difference for longer activities. Is there a way to set the synced calories from Garmin activities to use the active calories field instead of the total calories field?
Resting calories are calories used for your basal metabolism. So, logically, the longer the activity, the less the difference should become…
Active calories are measured during activity and resting calories during the rest of the day. Resting can only be recorded by a 24hr wearable (a watch) and not by, for example, a cycling head unit, which only records during activity (or in your case, Zwift).
Ok, but that’s not actually what Garmin reports when you record with an Edge. Take a four hour ride as an example.
319 here precisely reflects my resting calories times 4 hours. The kj to kcal approximation for the work done is the active calories, 2766. And Garmin reports the total of 3085 to intervals. If you record 2766kJ of work on Zwift however, it will report total calories without any “resting”, i.e. closer to 2788.
This is an inconsistency that can have a significant effect if you heavily train on either platform.